1. Field of the Invention
The present invention relates generally to the production of slide fasteners, and more particularly to a method of and apparatus for manufacturing a continuous slide fastener stringer chain including space portions devoid of coupling elements at longitudinal intervals.
2. Prior Art
According to a known method, a continuous slide fastener stringer chain having a pair of interengaged rows of continuous coupling elements sewn to a pair of continuous slide fastener stringer tapes along inner longitudinal edges, respectively, is intermittently fed in a longitudinal direction, and while the stringer chain is at rest, segments of coupling elements are cut off and removed to provide element-free space portions in the stringer chain at longitudinal intervals. With the known method, it has been observed that lines of stitching become slack at portions extending longitudinally across the element-free space portions with the result that endmost coupling elements, located next to the element-free space portions, are liable to be displaced. Such positionally unstable, endmost coupling elements hinder sliders from sliding thereover.
In another known method, a row of continuous coupling elements is intermittently supplied over one longitudinal edge of a continuous slide fastener stringer tape which is continuously fed to the sewing area of a sewing machine. The row of continuous coupling elements, while at rest, is severed into pieces of coupling elements to thereby produce element-free space portions between every adjacent pair of the pieces of coupling elements. Then the stringer tape is paired with a companion stringer tape into a continuous slide fastener stringer chain. The rows of coupling elements of severed length tend to be deformed or irregular in pitch under the influence of forces exerted thereon while they are fed before being coupled together, resulting in mismeshing of the coupling elements, particularly those coupling elements which are located next to the element-free space portions.